Insurance companies' definitions of collision and comprehensive claims differ so you will need to read through the terms of your policy and / or speak with your agent to determine which part of your physical damages portion of your policy you would make a claim.

In general, Collision coverage is intended to cover things that your vehicle strikes while Comprehensive coverage is intended to cover things that strike your vehicle. Comprehensive is supposed to cover un-excluded loss other than collision or overturn. It can be difficult to determine which occurrences are covered by collision and which is covered by "other than collision" (comprehensive) without discussing the issue with a representative from your insurance provider.

I have had a similar personal experience, my car's bumper has previously been hooked on a piece of rebar (the metal protruding from the concrete parking barrier) sticking up from what you referred to as the wheel bumper and pulled my bumper slightly off as you described happened to your vehicle. My agent stated that this would be considered a comprehensive claim; however I never placed a claim.

I found it to be cheaper to do the repairs to my bumper myself than it was to make a claim and pay the deductible. You may want to first find out the costs of repairing your bumper and then determine if the cost of repairs is more then your deductible or not and thus decide if you will make a claim or not.